Polycarbonate resins have excellent impact resistance and mechanical properties and exhibit excellent dimensional stability and wide colorability, and thus are widely used as housings for electrical and electronic products or as automobile components and the like.
Recently, in order to develop products having high-gloss textures, polycarbonate resins used for automobile exteriors have usually been subjected to coating processes. However, since such processes involve large numbers of steps, and have limitations, such as high defect rates, high incidence rates of harmful volatile substances, and increased cost, non-coating materials are being developed.
However, there have not yet been any examples in which a non-coating high-impact thermoplastic resin has been applied to an automobile exterior material. Although some polymethylmethacrylate (hereinafter referred to as PMMA) or PMMA/IR (impact rubber) products are being utilized in exterior components, PMMA is characteristically low-impact, and thus automobile manufacturers have called for the development of weather resistant, high-gloss, high-impact thermoplastic resins.
A weather resistant resin (AES resin) prepared by graft copolymerization of an ethylene-propylene-based rubber polymer (EPR, EPDM) and a predetermined amount of a mixed solution having styrene-based and acrylonitrile-based monomers dissolved therein is disclosed in Korean Patent Application Laid-open Publication No. 2006-0086194, but has reduced rigidity and scratch resistance when applied to polycarbonate resins, and thus has the limitation of being unsuitable for adoption in non-coating.
Korean Patent Application Laid-open Publication No. 2009-0110129 discloses a feature in which a resin composition including an acrylate-styrene-acrylonitrile (ASA) resin and PMMA is applied to an automobile exterior material. However, the disclosed resin composition has low heat resistance and impact strength, and has the limitation of poor mechanical properties.
A polycarbonate and a polycarbonate resin composition in which polyalkylaryl siloxane is added to a polycarbonate-polysiloxane copolymer are disclosed in Korean Patent Application Laid-open Publication No. 2012-0055277, but are inadequate for passing an automobile exterior weather resistance test, and also have weak scratch resistance.
A thermoplastic molding composition which includes a blend of a grafted rubber including a crosslinked rubber substrate that includes a styrene core and an acrylate rubber shell; a grafted phase grafted thereon, and a copolymer matrix including a copolymer such as styrene/acrylonitrile; and an aromatic (co)polycarbonate resin is disclosed in Korean Patent Application Laid-open Publication No. 2001-0108464 discloses, but has the limitations of poor gloss and poor scratch resistance.
Meanwhile, in Korean Patent Application No. 10-2013-0095189, the present inventors disclosed a polycarbonate-based thermoplastic resin composition capable of overcoming the limitations described above, but said polycarbonate-based thermoplastic resin composition was noted as having excessive impact strength, and as having scratch resistance that does not sufficiently satisfy the scratch resistance required for adoption in actual products.